A team member just found the following out about an inconsistency in the Rails documentation. Although:
https://github.com/rails/rails/pull/7188/files
indicates for the dependent option: “When no option is given, the behaviour is to do nothing with the associated records when destroying a record.”
Which is consistent with the behavior, but in:
(in the rdoc for associations), it states: “The default strategy is :nullify (set the foreign keys to nil), except for has_many :through, where the default strategy is delete_all (delete the join records, without running their callbacks).”
I think that last statement is a little unclear since it is no longer accurate in Rails 4, it seems. Magne on S.O. also noted this in the first comment of this answer: http://stackoverflow.com/a/16329482/178651
In addition, that might be helpful to mention somewhere in guides/source/upgrading_ruby_on_rails.md?
I’m not sure how to summarize/clarify that behavior at the moment in associations.rb (would just removing the sentence about the default strategy be ok?) or in which places “dependent: :nullify” should be added to models to ensure similar behavior from Rails 3 to 4 for the upgrade doc. Any ideas?
